The present invention generally pertains to centrifugal particle separators. More particularly, the invention relates to a construction which improves the functional, structural and volumetric characteristics of molded or cast inlet vane assemblies of centrifugal particle separators.
Generally, air precleaners are used for removing particulates from the air prior to introducing the air through an air cleaner or filter of an internal combustion engine. The function of the air precleaner is to remove as many contaminants from the air as possible before it flows into an air filter medium upstream from the internal combustion engine.
Precleaners operate on the principle of centrifugal separation. Outside air, with its entrained contaminants, is drawn into the precleaner by the vacuum created by the engine. The air and contaminants traverse a set of fixed, static, vanes which cause the air to circulate at a great speed. Centrifugal force throws the contaminants and moisture towards the outer wall of the precleaner. The contaminants follow the wall until they reach an opening where they are discharged back into the atmosphere or collected. Clean, dry air is then allowed to enter the air filter and subsequently the internal combustion engine.
Undesirable contaminants in the atmosphere include particulate matter such as dirt, dust, sand, snow and the like. While most engines include air filters which are meant to remove such contaminants from the air that feeds the engine, engine precleaners are also used in order to extend the life of the air filter and extend the engine's life.
As air precleaners work on centrifugal separation, greater air flow velocity will result in better separation between air and contaminants. As the velocity of air flow decreases, the centrifugal force on the contaminants also decreases reducing the separation efficiency of the precleaner.
Several different designs of air precleaners are commercially available in the marketplace. In one design, a precleaner uses a rotatable impeller or spinner to separate particles from air, discharge the dirty air and particle mixture circumferentially from a housing and direct the clean air to the air intake structure of an engine. The clean air moves centrally through a stack to the engine in response to a vacuum pressure on the air moving to the engine. Known air precleaners have also included a design in which air flows into the top of the precleaner and flows axially downwardly through the precleaner and into the intake stack of the engine. Also, some air precleaners are only useable when positioned in one orientation, i.e. positioned on a vertical axis or positioned on a horizontal axis.
Typically, air precleaners of molded construction utilize a centrifugal particle separator having a one-piece inlet vane. This inlet vane generally has a gap between each blade on the vane for tooling clearances. This gap (commonly referred to as a “shut-off” clearance) allows a portion of the air to pass axially through the particle separator, effectively bypassing the intended swirling route established by the vane blades. This “shut-off” clearance increases as the designed maximum flow of the precleaner increases. This necessitates a particle separator of an undesirably large axial and circumferential volume, having a narrow operational flow range and less than optimum separation efficiency.
Accordingly, it has been considered desirable to develop a new and improved centrifugal particle separator incorporating overlapping inlet vanes assemblies which would overcome the foregoing difficulties and others while providing better and more advantageous overall results.